Today, computer systems come in a host of different forms. They can range from the highly centralized, expensive, and powerful mainframes to versatile mid-range minicomputers and workstations, to the ubiquitous desktop and laptop personal computers. These various, separate computer systems can also be coupled together to form a computer network, thereby allowing end users to share files, application software, and peripheral hardware.
Attendant with most computer systems are data storage devices onto which digital data from the computer system is stored. In this manner, computer programs, textual information, graphics, and numerical data can be stored on a permanent basis for subsequent retrieval. There exists many different options for storing digital data. Some popular methods include optical and magneto-optical disk drives, tape drivers, and magnetic storage systems such as floppy disk drives.
Typically, these storage systems are fixedly attached within the computer system. This means that the computer system would have to be disassembled before the storage system could be physically removed. Hence, the data stored on these storage systems are physically tied to the host computer system and/or computer network. Hence, a person could not simply pick up and walk away with the storage unit containing the data. In many instances, the owner of the stored information is not only concerned about physically losing the data but is also concerned with keeping the stored information confidential. For example, the stored information might contain sensitive sales reports, marketing strategies, blueprints, manufacturing processes, customer lists, trade secrets, etc.
In order to safeguard the stored information, various schemes have been implemented to prevent unauthorized reading, copying, and erasing of the data by others. For example, one such security measure might require the input of a user identification number before that person is allowed to log onto the computer system. In addition, the user might be required to supply a secret password. Other security measures include encrypting the data, wherein the encrypted data is meaningless to unauthorized users. Only authorized users are provided with a means for deciphering the encrypted data. In short, when the storage mechanism containing valuable data is structurally integrated as part of the computer system, the computer's security protection prevents unauthorized access and tampering of the data.
Rapid advances in optical and magnetic recording technology have lead to smaller disk drives while storage capacity has increased. Furthermore, progress in the semiconductor field has led to the development of "flash" electrically erasable programmable read-only memory (flash EEPROM). The flash EEPROM is a non-volatile semiconductor memory in which digital data can readily be stored.
In order to take advantage of recent advances made in the storage technology, a group of computer and electronics manufacturers have formed the Personal Computer Memory Card International Association (PCMCIA) to define a set of standards for promoting interchangeability of data storage (i.e., memory cards) and peripheral expansion (i.e., I/O cards) among a variety of computer and other electronic products. The PCMCIA standard achieves interchangeability by defining a common set of physical dimensions, electrical interface, and data formats for the memory and I/O cards. The physical dimensions specify outer boundaries, mechanical tolerances, and connectors for the cards. The electrical interface section provides detailed pinout and signal definitions. The data format specifies the organization of the data on a card. The PCMCIA standard facilitates the introduction of small, portable, and lightweight memory cards based on either hard disk drive or flash EEPROM technology. These memory cards can readily be removed from its host computer system and later inserted back into the host system or some other PCMCIA compatible computer system.
This feature grants a user great flexibility and freedom in transporting the stored data. For example, a user can be writing a program, generating a report, updating a database, or otherwise working on a computer network at the workplace. The user can store the computer programs, database, etc. on the memory card. The memory card can be easily removed from the host computer system and placed in a shirt pocket, briefcase, or purse. This memory card can then subsequently be inserted into a laptop or notebook computer, thereby allowing the user to continue working on his other project. Later, the memory card can be removed and inserted in yet another PCMCIA compatible computer system (perhaps at home). Thus, users are free to travel and to take along their data with them in the form of memory cards so that the stored data can be accessed, updated, or edited on mobile computer systems or on computer systems other than their own.
However, along with the convenience associated with memory cards comes a problem in that memory cards can be misplaced, lost, or stolen. Whoever acquired the memory card could easily plug the memory card into a computer system and would have complete access and control over the data stored thereon. With a small, removable data storage mechanism, the user's host computer system can no longer safeguard the stored data.
Thus, what is needed is an apparatus and method for safeguarding data stored on a memory card from unauthorized access. It would be preferable for the safeguarding mechanism to impose a minimal burden on the user.